Voice-over-Internet Protocol (VoIP) is a technology that allows a user to make voice calls using a broadband Internet connection instead of a regular (e.g., analog) phone line. VoIP involves sending voice information in digital form in discrete packets rather than by using traditional circuit-committed protocols of the Public Switched Telephone Network (PSTN).
Video telephony includes technologies for the reception and transmission of audio and video signals by users at different locations, for communication between the users in real-time. Video telephony may be provided via several mechanisms, such as videophones, video conferencing, telepresence systems, and personal computer-based web cameras. Videophones and video-enabled mobile phones are usually used on a person-to-person basis. Video conferencing systems typically use digital Integrated Services Digital Network (ISDN) and IP transmission modes due to the need to convey very large amounts of data generated by cameras and microphones. Telepresence systems are a more advanced subset of video conferencing systems that allow greater degrees of video and audio fidelity. Personal computer-based web cameras are a modest form of video telephony typically used for point-to-point calls.
Quality of service (QoS) refers to resource reservation control mechanisms that provide different priorities to different applications, users, and/or traffic (e.g., data flows), or guarantees a certain level of performance to traffic. For example, a required bit rate, delay, jitter, packet dropping probability, and/or bit error rate (BER) may be guaranteed. QoS guarantees may be important if network capacity is insufficient, especially for real-time streaming multimedia applications (e.g., VoIP, online games, IP television (IP-TV), etc.), since these applications often require fixed bit rate and are delay sensitive.
The traditional method for deploying QoS to enable VoIP, video telephony, and other low-latency, bandwidth-limited applications is to negotiate QoS parameters for call set up and then police data flows in a network (e.g., a telecommunication network). Policing of the data flows is required because without policing there will be no value in the QoS. If every user (e.g., associated with a network) requests QoS for every application (e.g., used by the users), then the end result is that every user receives best effort treatment. In such a scenario, high bandwidth applications (e.g., web surfing, video downloads, etc.) are served just as effectively for the users whether or not the applications are provided via QoS over the network. In a “walled garden” or partly open network environment, the policing of the data flows can be implemented by checking ports being used and source and destination IP addresses against a pre-approved list. Such policing may be referred to as three-tuple and five-tuple QoS policing methods. With the advent of net neutrality rules and very open networks, the three-tuple and five-tupple QoS policing methods are ineffective. Thus, in open networks, more intrusive policing methods (e.g., deep packet inspection) are needed to ensure that only latency-sensitive applications are provided latency-advantaged QoS. However, such intrusive policing methods are time consuming and expensive to implement.